The present invention relates to isolators for rod ends, and especially those that include an elastomeric core. These rod ends include an outer member, an inner member and the elastomer component which lies between the two members to absorb vibration and to allow a certain amount of angular misalignment. The elastomeric component is strongly bonded to both members.
The basic concept is to utilize the incompressible characteristics of rubber when it is confined, to support large one-time or low cycle load events while still allowing for vibration isolation that is encountered by working loads. The invention also allows for an angular misalignment capability between members. This is accomplished by limiting the ability of rubber to deform elastically under high radial loads and without metal to metal contact of the inner and outer members.
This isolator design enables one to replace this standard elastomer rod with isolators that are of modified form without much or any major changes to the structure. Designs used in other applications, such as engine mounts or gear reduction mounts, have used cylindrical layers of rubber and metal. During high loading conditions, the rubber was essentially removed from the load path by the metal to metal contact on the inner and outer members.
The present invention prevents this metal component to metal component contact, and keeps the isolator in working condition. The cylindrical type of isolator does not allow for angular misalignment, whereas the spherical design does allow for a certain amount of angular misalignment.
One of the novel features of the invention is the provision of legs or dams at both ends of the inner member, which, in combination with the mold fingers or cutaway portion of rubber, allows the rubber to take on a unique shape. According to this unique shape, the rubber just then fills up the gap between the legs and the outer member, thus rendering it incompressible under high loading conditions, whereby there is no metal to metal contact. Yet, the arrangement does allows for misalignment of the parts to a certain extent, and of course allows vibration to be isolated over the working load range.
For example, one use of this design is for overhead stowage bin isolator mounts on passenger aircraft. The isolator is comprised of three components, an inner member, an outer member and an elastomeric element. The elastomer is bonded to both of these members and lies between the two of them. The exterior of the outer member is customarily cylindrical or banjo (rod end) in form.
The inner member uses a mounting bracket and a fastener extending there-through of generally rigid construction. The outer member carries the load and is able to isolate vibration with no difficulty. The novel features of the invention include the mold fingers which provide a space for the rubber to be compressed when subjected to load, and this rubber is confined in part by the two legs or the like, which are prevented from contacting the adjacent metal by reason of the legs' compression of the rubber into the previously unoccupied space. Accordingly, metal to metal contact is prevented, which would be damaging to the parts.
When in use, in one example, the isolator is able to support large, low-cycle loading events and greatly reduces the structure-borne noise in aircraft overhead stowage bins. These stowage bins, if mounted using standard metallic rod end bearings, would amplify the noise and vibration which is transmitted to them through their support structure. However, using the isolators of the present invention, they are able to take a certain amount of misalignment and, when loaded heavily, still not be deformed enough to render them ineffective.
Accordingly, it is an object of the present invention to provide an improved cartridge and rod end elastomeric isolator.
Another object is to provide a rod end isolator having a spherical or near spherical joint made from elastomer which is molded in-place between two specially made metal components.
Another object is to provide an isolator having a spherical portion with one leg or the like on each end of the inner member, with the legs being relatively thin and extending radially outward toward the outer member, but with a space in between the inner and outer members.
Another object of the invention is to provide a rod end isolator with a spherical segment made from rubber, but having on each end of the rubber a void created by a mold finger or the like for leaving this area free for engagement by the inner member legs.
Another object is to provide an inner member with such legs on its outer sides and having a cylindrical bore of increased length whereby to allow for twisting or other movement by the outer member.
Another object is to provide a rod end isolator which includes an outer diameter surrounding member, an inner member of increased width, with the two members having a bonded, relatively thin layer of elastomer separating them.